Bicycles are secured against theft with the aid of special locks. However, absolute security cannot be obtained; even the most stable and complicated locks can be opened by unauthorized persons with appropriate efforts. However, most locks offer good protection against spontaneous theft.
In the German Laid-Open Specification DE 42 32 540 A1, a lock for two-wheeled vehicles (with the wheels one behind the other) is described. The lock consists of a tubular container in which a centrally supported drum is arranged and around which a rope is wound. One end of the rope is fastened to the drum so as to be undetachable. The other end of the rope supports a safety lock half. To lock it, the safety lock half can be inserted into a second safety lock half fastened to the top end of the container so as to be undetachable.
The disadvantage of this bicycle lock and all other known bicycle locks is that it is fastened—if at all—to the bicycle with a special holding device and that the seat support and the seat connected with it are not included in the protection.